Manufacture of unchilled metallic castings by the centrifugal casting process



'Dec. 29, 1936. w. RIDLEYET AL MANUFACTURE OF UNCHILLED METALLICCASTINGS BY THE GENTRIFUGAL CASTING PROCESS 3 Sheets-Sheet 1 Filed Nov.27, 1955 wg fr 3 Sheets-Sheet 2 ///w #5 M M Q m Q 6 w v /K /%//v//. M AA W. RIDLEY El AL MANUFACTURE OF UNCHILLED METALLIC CASTINGS Dec. 29,1936.

BY THE CENTRIFUGAL CASTING PROCESS Filed Nov. 27, 1955 Patented Dec. 29,1936 UNITED STATES PATENT OFFICE MANUFACTURE OF UNCHILLED METALLIQCASTINGS BY THE CENTRIFUGAL CAST- ING PROCESS William Ridley, Beeston,Nottingham, and Percy Hutchinson Wilson, Nottingham, England ApplicationNovember 2'1, 1935, Serial No. 51,926

y In Great Britain December 24, 1934 10 Claim.

This invention relates to the manufacture of metallic castings such forinstance as pipes by centrifugal casting processes in which use is madeof dry pulverulent materials which are introduced 5 into the rotatingmould prior to and preferably closely in advance of the introduction ofthe molten metal, so as to produce a film or lining on the interiorsurface of the revolving mould for the essential purpose of preventingthe chilling of the casting. Various powdered materials have beenemployed to that end and satisfactory results have been obtained by theuse of ferrosilic'on or aluminium or a substance including aluminium inmetallic form. I

Various methods also for introducing the powdered material into themould have been devised, a. common practice residing in the use eitherof a suitable container in the form of a shallow trough charged with aquantity of the i powdered material and adapted to be tipped principleinvolved according to the present invention resides in the use of areciprocating carrier'or propulsion tube or conduit moving, according toa preferred arrangement, inside an outer sleeve or casing, forwardmovementor discharge of the material being effected by arresting theforward stroke of the carrier tube as by a sudden stoppage of auniformly accelerated feed, stroke thereof followed by a quickwithdrawal or rapid initial acceleration of the carrier tube on itsreturn stroke with a view to effecting propulsion of the powderedmaterial by a combination of jarring and quick withdrawal of the carriertube from under the material at the forward end-of the stroke whileproperly controlling these movements between the ends of the respectivestrokes.

The reciprocating action of the carrier tube or the like may be obtainedmechanically, for example by means or under the control of anappropriately designed cam gear or electromag netically such as by meansofan electromagnet of a convenient type.

The invention also consists in methods and' apparatus as set out moreparticularly in the appended claims,. including in particular the methodof feeding finely divided material into a region of a rotary mouldrelatively remote from the supply, which consists in discharging saidmaterial from said supply on to a surface extendible to such region andimparting to said surface and material thereon a longitudinal forwardmovement towards said region, arresting said movement suddenly andrapidly accelerating said surface in reverse direction 'for withdrawingit from under materlal'moved forwards therewith in the preceding stroke,repeating said forward and reverse movements at a relatively highfrequency to efiect a desired-rate of feeding. It also includesapparatus for use with centrifugal casting machines, comprising a memberconstituting a conduit of elongated form. adapted to be inserted into arotary mould, means for depositing finely divided mould-coating materialin one end of said member, and means for subjecting the latter tolongitudinal reciprocatory or vibratory movement including a sharpdetermination of thatstrokeof said movement which is directed to theopposite end of said member and rapid initial acceleration during thefollow- ,in stroke.

Referring now; to the accompanying drawings:

Figures 1' and 1a are complementary longitudinal sectional views of acentrifugal mould apparatus incorporating one form of the presentinvention;

Figure 2 is a fragmental cross-section of the metal-charging trough andassociated powder supply conduit included in Figure 1;

Figure 3 is a side elevation of a form of powder supply actuatingmechanismalternative to that included in Figure 1; j

Figures 4 and 5 are side elevation and plan views respectively of a;preferred construction of 40 the type of powder supply actuating deviceshown in Figure 1. p

Referring now to the drawings, which, show one convenient constructionof apparatus in which the invention may be carried into efiect, andignoring at first the specific means used for producing theaforementioned reciprocatoryor vibratory action, the reciprocating orbarrier tube a is arranged for protection inside an outer sleeve or tube2) the latter being stationary and placed preferably under the liningblocks 0 forming part of the usual metal runner or casting trough d ofthe centrifugal casting machine which is retractable in relation to themould. The inner or carrier tube a projects at the delivery region e 55beyond the outer tube b. and is with advantage peripherally perforatedat or to-allow the drypowdered, material to fall through and distrib-'ute itself uniformly in the form of a relatively wide ribbon on thesurface}! ofthe mould at a suitable distance in" advance of thedeposition of the molten metal which takes place over the end d1 of therunner trough. At its other end this inner orcarrier tube is connectedas by a bend a or a branch or 'T-piece 91 to a suitable receptacle hcontaining the dry powdered material, such for instance as form-silicon.This receptacle can be either, as shown, stationary and connected to thecarrier tube by means of a flexible pipe 1 or can be arranged to movewith the tube.

For the electromagnetic actuation of the carrier tube a the devicesreferred to can'be either of the plunger'solenoid type (see Figure 3)for direct current operation, or alternatively a contactor type ofmagnet for alternating current as embodied in Figure 1. Each magnet willbe operated at the required frequency which will depend upon the nature,state of subdivision,-.

fluidity of the material and other factors, including the rate ofdelivery req m 1n the D. C. type of actuator, current is suppliedthrough an interrupter or distributor to a coil 1 surrounded bya polelimb. This coil, when energized, attracts an armature in the form of aplunger n passing through the centre of the coil,

, the plunger being suitably connected as by way of the branch piece or'T "or to the carrier or propulsion tube a which delivers the material tothe end of the casting trough.

The plunger or armature n as shown in Figure 3 is provided with anadjustable dashpot indicated by m, air, liquid or friction being themedium, to provide suitable retardation of the 1 movement and the .Onedistributor capable of supplying current to .any number of machinescould be used.

In the case'when'an A. 0. supply is to be used, and referring to Figure1, current at any suitable periodicity may be supplied direct to thecoil 1m surroundings pole limb, which in turn attracts an armature ncoupled by suitable'means, e. g.

through a sort of parallel motion linkage system o, 01, to the carrieror propulsion tube a. Slow stopping and starting of the returnandforward stroke respectively is obtained by incorporation of suitabledashpot means similarvto that embodied in the D. C. equipment, oralternatively and as actually shown, by means of an auxiliary springinserted as at :1 in lever part 0 of the coupling between the armatureand the propulsion tube.- This spring would be strong enough to overcomethe static friction of the tube, but would be compressed to a limitedextent in overcoming the inertia of same. Such an arrangement provides agradual slowing clownof the tube on the return stroke, and a gradualspeeding up of same on the forward stroke, while at the same timepermitting sharp metal to metal contact at the end of the forwardstroke, and

thereby providing the necessary jarring action to the material andconsequent propulsion thereof and discharge from the tube.

In the construction shown in Figures- 4 and 5, an armature element nvibrated by the action of the coil on is attached at one end by a pivotm to the magnet body and also pivotally to a bridge member us, one endof which is secured as shown to the bend 91 and thereby to thepropulsiontube a. The member as which embraces the magnet is attached atits opposite end to guide means n4 adjustable within a support as, andis operatlvely connected also at each end to leaf springs as in such away that the entire bridge member and positively connected partsmayreciprocate or vibrate .with the armature element 12. against theresilient action of the springs, to an extent regulatable by theadveniently indicated by a pointer m and dial m. The impact of metal tometal above mentioned occurs, as most clearlyseen in Figure 4, at thenut and/or washerv faces at me, which are separated axially when thetube a is retracted by the magnet armature but which would otherwisebear together under the action of thesprin gs-ns.

Control of the amount of material. p h lied may be effected by varyingthe gap of the agnet as by a handwheel and consequently the stroke ofthe tube, this variation being suitably registered on a dial; oralternatively 'by'inserting a potentiometer in series with the coil soas. to vary the justment nut devices at m collectively; and convoltageenergizing the same, thereby varying the strength of the magnetic pull.By this means remote control of the apparatus is readily eifected.

vIn practice this form of apparatus has been found to be more positive,in its action than any other form known-I at present. and to ensurereliable application of a more uniformiilm of powdered material in themould and in the correct relation to the point of the metal depositiontherein. 7 Having nowdsscribed'om' invention. what we ent is:- a 1.Apparatus for feeding ilnelydivided powder over the interior of a rotarymould, comprising a,

chimasnmand-deairatosecurebyhetterslab' member entrable into andrelatively longitudb" naliymovableinsaidmouldapowdermpply containerattached to saidmember, means generally movable with said member andproviding.

a surface extendiblefrom said container into said mouldsaidmeansbeingreciprocable in relationtosaidmembenmeansfordischargingsaid,

P wder from said container on to said surface. driving means forreciprocating said reciprocable means in relation to said member andmeans governing the action of said driving means for arresting suddenlythe forward strobe towards the mould interior and producingacoelerationduring the reverse stroke thereby withdrawing said surfacefrom under powder moved forward therewith in said forward stroke,said-driving means being operable at a relatively high frequency toeffect feeding at a desired rate.

2. Apparatus according to claim 1, in which said driving means producesa uniformly accelerated forward stroke of said reciprocable means andsaid governing means includes stop means operative to sharplyarrest-said forward strokeand spring-meansoperative to effect rapidinitial acceleration in the reverse stroke, thereby effecting generalforward mo of the material along said surface by a' quick withdrawal ofthe surface from under the material.

on'ofiarringand 3. Apparatus for use with centrifugal casting machines,comprising a metal-charging trough. a member constituting a conduit ofelongated form adapted to be inserted with said trough intoa rotarymould, meansi'or depositing finely divided mould-coating material in oneend of said member and means for subjecting the latter to longitudinalreciprocatory or vibratory movement in relation to said trough, saidmovement including a sharp termination of that stroke thereof which isdirected to the opposite end of said member and a rapid initialacceleration during the following stroke.

4. In centrifugal casting apparatus a rotary mould; an external supplyfor finely divided material, a conduit for conveying said material fromsaid external supply into the mould interior, means axially advanceableand retractable in relation to said mould said means forming a supportfor said conduit for the general movement thereof into and out of themould, means enabling the conduit to be reciprocated longitudinally inrelation to said support-forming means, and means for reciprocating saidconduit for propulsion of said material along the same into the mould.

5. Apparatus according to claim 4 wherein said support-forming meansconsists of a runner trough for the introduction of metal to be castsaid conduit being of tubular form reciprocatable within guiding meanscarried by said trough, and terminating in a powder-discharging end notgreatly removed from the metal-discharging end of said trough.

6. Apparatus according to claim 4 wherein said support-forming meansconsists of a runner trough for the introduction of metal to be cast.

said conduit consisting of a tube reciprocatable protrude in adischarging end not greatly removed from the discharge end of saidtrough.

7. Apparatus in accordance with claim 4, in

which said reciprocation means comprises an electro-mechanical vibratordevice operative between said conduit and said support therefor.

8. Apparatus according to claim 4, in which said reciprocation meanscomprises an electromagnetic vibrator device operatively coupled to saidconduit and the support therefor through means introducing dissimilarityin the strokes constituting a vibration.

9. Apparatus according to claim 4, in which said reciprocation meanscomprises an electro-magnetic vibrator device operatively coupled tosaid conduit and the support therefor through means introducing anabrupttermination to that stroke of a vibration in the direction fromthe supply towards the mould, and uniform acceleration and retardationduring the remainder of such vibration.

10. Apparatus according to claim 4, in which said reciprocation meanscomprises an electrosaid conduit and the support therefor through meanscomprising resilient means imparting unia 30

